In his last educational dvd “Secret weapon’s of the modern drummer“, His Majesty Jojo Mayer deals with one of The Holy Questions of Drumming: matched or traditional grip?
Endless discussion are held on this point, with no winner. Supporters of each tecnique can list a number of reason their choice is better. Jojo, who plays mainly traditional, but masters matched too, adds an interesting argument to the debate.
Matched (french, german and their variations) grip is symmetric; traditional grip is asymmetric, where asymmetry can help your body ‘think different’, put in contrast left and right, mind and heart, consciousness and unconsciousness. With matched grip – Jojo says – you can develope and equal dexterity of left and right of your body, making them more similar; with traditional grip you develope the difference, leaving your body surprise you.

I find this concept very interesting. I switched from traditional to matched grip when i was 20, after 9 year studying traditional grip: i’m always surprised how my left hand ‘remember’ how to play traditional and how some kind of stuff (eg. pressed rolls) come for me more confortable using traditional grip. Maybe because i’ve learned it when i was so young.
Traditional grip is an heritage of military drums, when drummers played marching. We play drumset seated and, imho, matched is the right choice. If you are a professional, anyway, is a really good idea to practice traditional grip too, as well all kind of matched grips. Maybe your body can surprise you

Resources related to matched and traditional grip
1. Matched grip article on wikipedia, discussing the three main matched grips: French grip (finger controlled), German grip (wrist controlled) an American grip (hybrid of french and german grips usind both wrist and finger control)

2. Traditional grip (also known as Orthodox grip) article on wikipedia, discussing the grip descending from marching drums with overhand grip on the right hand and underhand grip on the left

2a. Moeller Method, an article on wikipedia on this controversial method that combines a variety of techniques with the goal of improving hand speed, power, and control